Heating apparatus



June 19, 1945.

H. J. DE N. Mc'coLLuM HEATING APPARATUS Filed Oct. 6, 1942 2 Sheets-'Sheet 2 parent as the description proceeds.

oi the heat transfer means;

Patented June 19, 1945 Henry J. De N.

McCollum exec Collum, deceased McCollum, Chicago, 111.; Thelma utrix of said Henry J. De N. Mc-

Application October a, 1942, Serial so, 460,968

ii'Clalms. (Cl. l26.ll6)

My invention relates to heating apparatus and of the internal comof the fins and particularly that portion adjacent the outlet end of the heater.

Fig. 5 is a view similar to Fig. l, but showing a modified form of my invention;

Fig. 6 is an enlarged view taken' in the same plane as Fig. 5 and illustrating more clearly the arrangements for admitting secondary air; and

Fig. 7 is a view on an enlarged scale showing a partial, transverse section and is taken on the line 1-! ct Fig. 5.

In Figs. 1 to 4, inclusive, I have illustrated my invention as being embodied in heating apparatus comprising a heater having an air inlet Iii which There is a practical limit-to the temperature to which the tin; can be heated and this limits the total quantity of heat which can be given oil by a heater 01' any given size and shape.

' An object of my invention is to provide heating apparatus of the internal combustion type in which local hot spots are hollow fins and the heat transfer means is heated new and improved my invention is to provide heating apparatus which is extremely compact, light in weight, and has a high heating output.

Other objects and advantages will become In the drawings: i Fig. 1 is a View showing a longitudinal section through a heater embodying my invention;

Fig. 2 is an enlarged view taken on the same plane as Fig. 1, but showing more clearly the manner in which the secondary air is admitted to the heater;

. Fig. 3 is a' view showing a partial, transverse section and is taken on the line 3 -3 of Fig. 1:

Fig. 4.15 a plan view oi a section of the inlet end eliminated from the air by a fuel supply pipe H mixture of fuel and having openings ii at the throat of the Venturi tiblemixture formed in the Venturi tube i2 flows t l'oush ports II in a burner tube 20 and enters the combustion chamber 22 where the combustible mixture is ignited by an electrical igniter N.

This igniter may be provided with the usual thermostatic switch for cutting of! the current to the igniter when the heater reaches operatingv temperature, and thereafter ignition is maintained by a reigniter 26.

A flarin plate 28 or heat exchanger tending lengthwise 30 having hollow fins 32 exthereof. A muiiler 34 is 10- metal shell 38 containing a quantity of glass wool 38 or stainless steel wool, or other suitable material. The shell 36 has openings 40 communicating with the passages l2 in the interior of the hollow fins 32 and these-openings l0 constitute acoustic couplings betweenthe passages 42 and the interior oi the muiller ll.

The outlet end of the heat exchanger 30 is closed by a plate II which cooperates with the adjacent end of the mufiler 34 to form an outlet chamber 48. An'outlet fitting 48 serves to con nect the outlet chamber II with any suitable exhaust pipe attached to the threaded end" of the exchanger Il,'due to the tapered shape 01' the end of the muiller adjacent the combustion chamber. This extension or the passage 52 as it approaches the heat exchanger I0, permits the hot gases from tube II. The combusserves to connect the discharge and oi. the combustion chamber 22 withthe inletend of a tubular heat transfer means e combustion chamber initially to contact the fins 82 are most aptto cooperates with the 2,. heat exchanger "over an appreciable portion of its length and by thus spreading out the gases of combustion and distributing them lengthwise of the heat exchanger, the formation of local hot spots in the hollow fins is avoided. The extreme end of the muilier 8 is protected from the buming gases in the combustion chamber by a hollow cap 58 formed of nichrome or other heat resisting material.

In order to insure the elimination of all hot spots from that portion of the heat exchanger with which the hot gases first come in contact, I have provided means for'admitting secondaryair which cools the inlet end of the heat exchanger and mixes with the products of combustion flowing from the combustion chamber and serves to reduce somewhat the temperature of these gases. Since the bases 58 of the hollow develop hot spots, my novel arrangement for introducing secondary air is particularly designed to cool the bases of the hollow fins adjacent the inlet endof the heat exchanger 38. This means assumes the form of curved sheet metal fingers. 58 which cooperate with the side walls and bases of these fins to form ducts 68 which direct secondary air into the passage 52 throughan annular series of openings 52 formed in the bases 56 of the hollow fins.

The ends of the hollow fins 32 are directed inwardly and arranged in overlapping relationship, as indicated at 88 in the cut away portion of Fig. 4. The fingers 58 are seam welded along their edges to the sides of the hollow fins, as indicated at 88 and 58 and the curved lower end of each finger 58 is seam welded to the base of a fin, as indicated at 18.. The fingers 58 are shown as integral extensions of an air supply tube I2 and this tube is-seam welded to the closed ends of the hollow fins, as indicated at". The tube I2 is supplied with air from the inlet l8 by way of a connecting cone 14 so that part of the air flowing through the inlet l8 passes into cone l4 and tube 12 and thence through duct 88 and openings 82 into passage 52. I

The secondary air flowing throught the ducts 68 cools the adjacent portions or the hollow fins 32 and particularly the bases 55 thereof at the portions where the hot gases of combustion contact these bases near the outlet of the combustion' chamber. S nce the portions of the fins which are cooled by this secondary air are those portions which are most likely to develop hot spots, my novel-means for admitting secondary air serves to eliminate hot spots from the heat exchanger and, therefore, permits the entire heat exchanger to be operated at a higher and more efiicient temperature.

The secondary air flowing into the passage 52 mixes with the products of combustion therein and this slightly cools these products of combustion. The products of combustion with the thus it may be satisfactory Preferably the ventilating air inlet 88 and the inlet l8 iorthe secondary air and air for the combustible mixture are connected to separate blowers or rams, .although under some condito supply both of these inlets with air from a common ram or blower or other similar means. The outlet of the casing 88 may communicate directly with the aircraft cabin or other space to be heated, or witha duct system for distributing the heated ventilating air to several different points.

The embodiment shown in identical with the embodiment of Figs. 1 to 4, inclusive, .except that in the embodiment of Figs. 5, 6 and 7 the tubes 88 are inserted in the openings 82 and are secured therein by riveting over the upper'ends of the tubes, as indicated at 82. in Fig. l in that the tubes 88 conduct the secondary air to the center or the passage 52 and midway between opposite sides of the passage, so that the secondary air mixes thoroughly with the products of combustion flowing from the combustion chamber 22 to the heat exchanger 88. For certain purposes this modification of my invention is more desirable than the form shown in Fig. 1 in that the tubes 98 conduct the secondary air to the center of the passage 52 and prevent this secondary air from forming a heat insulating blanket between the products of combustion and 88 immediately to the left of the opening 82.

It isto be understood that my invention is not limited to the details shown and described, but may assume numerous other forms and that my invention is to be construed as including all varicomprising a tubular secondary air entrained therein then flow into the passages 42 in the hollow fins. After the products of combustion have traveled the length of the hollow fins, they enter the outlet chamber 48 and are discharged through outlet fitting 88 to atmosphere.

The heater is enclosed in a casing 88 which heat exchanger 88 to form ventilating air passages 82 between the hollow fins 32. The inlet end of nected to a cone 84 communicating with a ventilating air inlet 88 supplied with ventilating air mm a ram, blower, or other suitable means.

the casing 88 is con-- ations and modifications falling within the scope of the appended claims.

I claim:

1. Heating apparatus of the class described,

hollow finned heat exchanger, a combusion chamber for supply ng hot products of combustion to one end of said heat exchanger, means cooperatingwith th bases of the hollow fins to form ducts adjacent the inlet end of the heat exchanger, said heat exchanger having openings connecting said duets with the interior of said heat exchanger, means for sul plying secondary air to said ducts, and means for directing ventilating air over said heat exchanger.

2. Heating apparatus of the class described, comprising a tubular heat exchanger having hollow fins provided with sides and bases, curved fingers located between the sides of said hollow fins and cooperating with said sides and the bases provided with openings establishing communication between said air ducts said heat exchanger, a combustion chamber. for supplying hot products of combustion to said heat exchanger, means for supplying secondary air to said ducts, a muflier located in said heat exchanger, and means for directing' -ventilating air over said heat exchanger.

'8. Heating apparatus of the class described. comprising a tubular heat exchanger having hollow fins provided with sides and bases, curved fingers located between the sides of said hollow fins and cooperating with said sides and the bases of said fins to form air ducts, said bases being provided with openings establishing communication-between said air ducts and the interior of said heat exchanger, a combustion chamber for supplying hot products of combustion to said heat exchanger, means for supplying secondary air to Figs. 5, e and '1 is that portion of the heat exchanger comprising a tubular heat exchanger having holcomprising a tubular heat exchanger having holprovide seoondaryair ducts. a combustion chamwith the outlets or said duct and extending rathe combination or a tubular finned heat exlow fins to provide a passage for flow of hot gases ducts with the interior of said heat exchanger, 9. Heating apparatus comprising a tubular cooperating with said fins to form secondary air gages said fins, and means for supplying cooler aware: 3

said ducts; and means !or directing ventilating foadinectingv'entilating-air over said air over said heat exchanger. heat ex 4. Heating apparatus or -the class described, 7. Heating apparatu of the class described,

lowfins provided with sides and bases, curved low fins, means for supplying hot gas to said fins,

her for supplying hot gases to said end of the heat dially inward therefrom; and means for directing exchanger, ,means for supplying a combustible ventilating airov'er said heat exchanger. mixtm-e to said combustion chamber and for sup- 8. Heating apparatus or the class described, plying-secondary air to said ducts, other means comprising a tubular heat exchanger having hoiior directing ventilating air over said heat ex- 10w fins extending lengthwise thereof. a combuschanger, and a muiiierlocated in said heat extion chamber for supplying hot gases to one end changer. of said heat exchanger, a muiiier located in said 5. In heating apparatus or the class described; heat exchanger; and cooperating with said holchanger, a combustion chamber for supplying irom" said combusion chamber to said heat exhot gases to one end of said heat exchanger, changer. means for directing secondary air over fingers cooperating with said fins to form sec 2 the ends of Said fins adiacent said combustion ondary air passages adjacent the bases of said chamber and radially inward to approximately fins and at said end of the heat exchanger, said the center or said Passage. and means for directheat exchanger having openings connecting said ing ventilating air over said heat exchanger. means for supplying secondary air to said ducts, heat exchanger having hollow fins extending andfmeans tor directing ventilatitng air-over said lengthwise thereoi. means for supplying hot fluid heat exchanger. to the interior of said hollow fins adjacent one 6. Heating apparatus of the class described, end of said'heat exchanger, said heat exchanger comprising a tubular heat exchanger having fins including a plurality of cooling air-tubes between extending lengthwise thereoi, a combusion chamsaid fins and radially arranged adjacent said end heat exchanger, fingers located at said end and ing air into said hot i luid before said fluid enducts, tubes communicating with said ducts and fluid to the exterior oi said fins and to said air projecting radially inward therefrom, means for tubes. supplying secondary air to said ducts and tubes, HENRY J. DE: N. i 

